This study evaluated the mid-term results of the modified maze procedure using cryoablation for treating atrial fibrillation associated with rheumatic mitral valve disease. Between March 2000 and February 2004, 177 consecutive patients underwent the modified maze procedure using cryoablation concomitant with mitral valve surgery, were divided into the modified Cox-Maze III (group CM, n=88), modified Kosakai-Maze (group KM, n=63) and left atrial maze (group LA, n=26) procedures. Postoperative and follow-up results were analyzed and compared between the groups, with a mean follow-up time of 22.4+/-15.1 months. There were three hospital deaths (1.7%). The operative time was significantly longer in the group CM than the KM or LA groups, respectively. One late death developed in the CM group. At last follow-up, 139 patients had sinus rhythm (79.9%), which was regained in 67 CM (77.9%), 50 KM (80.7%) and 22 (84.6%) LA group (P=0.743) patients. Freedom from stroke at 4 years was 84.6% in the CM, 95.0% in the KM, and 92.9% in the LA (P=0.916) groups. There were no significant differences in the sinus conversion or stroke rate between patients with the left atrial appendage preserved and those with it excised or obliterated. The modified maze procedure using cryoablation is safe and effective, with an acceptable sinus conversion rate and clinical improvement.